+/*
+ * This file is part of the GROMACS molecular simulation package.
+ *
+ * Copyright (c) 2021, by the GROMACS development team, led by
+ * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
+ * and including many others, as listed in the AUTHORS file in the
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+/*! \libinternal \file
+ * \brief Defines helper functions for mdrun pertaining to free energy calculations.
+ *
+ * \author Pascal Merz <pascal.merz@me.com>
+ * \ingroup module_mdrunutility
+ * \inlibraryapi
+ */
+
+#include "gmxpre.h"
+
+#include "freeenergy.h"
+
+#include <numeric>
+
+#include "gromacs/mdrun/replicaexchange.h"
+#include "gromacs/mdtypes/awh_params.h"
+#include "gromacs/mdtypes/inputrec.h"
+
+namespace gmx
+{
+
+int computeFepPeriod(const t_inputrec& inputrec, const ReplicaExchangeParameters& replExParams)
+{
+ if (inputrec.efep == FreeEnergyPerturbationType::No)
+ {
+ return 0;
+ }
+
+ // Set free energy calculation period as the greatest common
+ // denominator of nstdhdl, nstexpanded, replica exchange interval,
+ // and AWH nstSampleCoord.
+ int nstfep = inputrec.fepvals->nstdhdl;
+ if (inputrec.bExpanded)
+ {
+ nstfep = std::gcd(inputrec.expandedvals->nstexpanded, nstfep);
+ }
+ if (replExParams.exchangeInterval > 0)
+ {
+ nstfep = std::gcd(replExParams.exchangeInterval, nstfep);
+ }
+ if (inputrec.bDoAwh)
+ {
+ nstfep = std::gcd(inputrec.awhParams->nstSampleCoord(), nstfep);
+ }
+ return nstfep;
+}
+
+} // namespace gmx